European Union chiefs are drawing up plans for a single “Treasury” to oversee tax and spending across the 17 eurozone nations.

The proposal, put forward by Herman Van Rompuy, the European Council president, would be the clearest sign yet of a new “United States of Europe” — with Britain left on the sidelines.

The plan comes as European governments desperately trying to save the euro from collapse last night faced a new bombshell, with sources at the International Monetary Fund saying it would not pay for a second Greek bail-out.

It was also disclosed last night that British businesses are turning their back on Brussels regulations to give temporary workers full employment rights, with supermarket chain Tesco leading the charge.

Meanwhile, David Cameron is attempting to face down a rebellion tomorrow by Tory MPs in a vote over staging a referendum on Britain’s membership of the EU.